This project represents a systematic study of immunologically mediated injury to cultured endothelial cells, and the resultant effects of this injury on the structural, functional and biochemical parameters of cultured endothelial cells. Additionally, the role of endothelial cells in modulating inflammation and tissue damage by elaboration of pro-inflammatory and anti-inflammatory factors will be evaluated. Specifically, murine (rat and hamster) and human pulmonary endothelial cells will be maintained in culture for studies of the production of pro-inflammatory factors (chemotactic and vasoactive factors, complement components and tissue thromboplastic activity) and anti-inflammatory factors (chemotactic factor inactivator). The effects of soluble leukocytic, macrophage lymphocyte products (including enzymes, oxygen metabolites, lymphokines), the complement system (cytolytic effects), and complement factors (C5a and C3a) on the functional and biochemical integrity of the cultured pulmonary endothelial cells will be measured. Parallel experiments utilizing normal and activated leukocytes (polymorphonuclear leukocytes, mcarophages, and cytotoxic T-lymphocytes) will evaluate the effects of cellular mediated injury on cultured endothelial cell function. Finally, we will develop multi-component in vitro models consisting of pulmonary endothelial cells, fibroblasts, smooth muscle cells, basement membrane and collagen to study the response of endothelial cells to direct and indirect immunologically mediated injury. These studies will focus on the interplay of endothelial cell and non-endothelial cell components of the capillary unit in the initiation, amplification and suppression of inflammation and tissue injury. These studies will provide a comprehensive picture of the structural, functional and biochemical responses of pulmonary endothelial cells to immunologically mediated injury.